Reduce avoidable load safely
- Keep exterior doors and windows closed while cooling
- Use shades on sun-exposed windows and postpone major heat-producing activities when practical
- Keep filters, returns, and supply vents clear
- Avoid repeated large thermostat changes
Document the pattern
Note outdoor conditions, indoor temperature, thermostat setting, run time, airflow, humidity, and whether performance recovers after sunset. This helps distinguish a one-time extreme condition from a persistent capacity or system problem.
Avoid quick conclusions about size
Poor performance can involve the equipment, ducts, controls, airflow, installation, maintenance, or the building envelope. Oversizing also creates comfort and humidity tradeoffs, so replacement sizing should be based on a proper load calculation rather than matching an old nameplate automatically.